1) Biospecific interaction analysis using BIAcore instrumentation, and in vitro infection experiments, have been used to further demonstrate the importance of the CDR2 and CDR3-like domains of CD4, the receptor for HIV, for virus binding and post-binding viral entry events in HIV infection. 2) The relationships between reactive astrogliosis, altered neurotransmitter regulation in selected populations of cerebrocortical neurons, and motor/cognitive function have been delineated in simian immunodeficiency virus-infected rhesus monkeys with motor/cognitive impairments. 3) Attempts to colonize murine brain with bone-marrow derived cells tagged with retroviral expression vectors have been successful, suggesting that inflammatory cells of hematopoietic origin might be genetically altered ex vivo to provide therapeutic products at otherwise inaccessible sites of inflammation in the HIV-infected central nervous system.